Comparison of In Vitro Heat and Cold Tolerances of the New Invasive Species Bactrocera invadens (Diptera: Tephritidae) With Three Known Tephritids

Abstract

Bactrocera invadens Drew, Tsuruta & White (Diptera: Tephritidae) is spreading throughout central Africa attacking a variety of fruit; quarantines are placed on fruit from this region that are considered hosts. The only phytosanitary treatment that is commercially available is an ionizing irradiation treatment for all Tephritidae at 150 Gy. The development of other treatments, such as heat, cold, or fumigation, usually requires testing tens of thousands of insects at a dose that provides efficacy and may take several years. It may be possible to shorten the time required to develop treatments by comparing tolerance of a new quarantine pest to tolerances of pests with similar behaviors and modes of infestation for which treatment schedules are available. Cold and heat tolerance ofB. invadens was compared with tolerance of Anastrepha ludens (Loew), Bactrocera dorsalis (Hendel), and Ceratitis capitata (Wiedemann) in vitro. Third-instar B. invadens was no more cold tolerant than the other species when treated in diet at 0.94 +/- 0.65 degrees C and no more heat tolerant than C. capitata when immersed in vials in water at 44.7 +/- 0.1 degrees C. The data at 0.94 +/- 0.65 degrees C was used to include B. invadens in a USDA cold treatment schedule for citrus fruit from Africa so that trade would not be interrupted while protecting U.S. agriculture from this invasive pest.

Population structure of a global agricultural invasive pest, Bactrocera dorsalis (Diptera: Tephritidae)

“…Given such consistent results from multiple studies, we consider it highly unlikely that different geographic populations of the fly will show marked biological differences, such as differences in host use or thermal tolerances, which might impact on quarantine, trade, or pest management. Indeed, where post‐harvest market access research has been done on different geographic populations of B. dorsalis , no significant differences have been detected between populations (Hallman, Myers, Jessup, & Islam, ; Myers, Cancio‐Martinez, Hallman, Fontenot, & Vreysen, ), a result consistent with the lack of population structuring.…”

Development of Phytosanitary Cold Treatments for Oranges Infested With <I>Bactrocera invadens</I> and <I>Bactrocera zonata</I> (Diptera: Tephritidae) by Comparison With Existing Cold Treatment Schedules for <I>Ceratitis capitata</I> (Diptera: Tephritidae)

“…Grout et al (2011b) concluded that the most cold-tolerant stage was the second instar based on a commodity group research report from South Africa (Ware et al 2005). Hallman et al (2011) cited PowellÕs (2003 analysis of historical cold treatment data for C. capitata as supporting the third instar to be the most cold-tolerant stage. A summary of studies of most cold-tolerant stage of C. capitata follows.…”

“…This effort would eventually culminate in broad generic treatments that would be applicable across groups of pests and commodities, including some for which no research was done (Hallman 2012 Hallman et al (2011) found that third instar B. invadens was no more cold tolerant than third instar Anastrepha ludens (Loew), Bactrocera dorsalis (Hendel), and Ceratitis capitata (Wiedemann) in vitro at 0.94 Ϯ 0.65ЊC. That information was used to allow cold treatment schedules for these three species to be used for B. invadens on an emergency basis (USDA 2013).…”

Cold Susceptibility and Disinfestation of Bactrocera invadens (Diptera: Tephritidae) in Oranges

“…The energy required to form a pupa would probably result in some mortality of weak surviving larvae but without a direct comparison we cannot speculate about the equivalence of this mortality in terms of days of treatment or lower treatment temperature. Recent results from small-scale (no survivors from 104 larvae treated for 11 d) incubator studies in media showed that B. invadens was no more cold tolerant than C. capitata when treated at a mean temperature of 0.94ЊC (Hallman et al 2011). Our exposure of 21,784 third instars to 1.1ЊC for 11 d resulted in 27 survivors (Table 4), so perhaps if the comparison of Hallman et al (2011) was repeated with larger numbers a different result may be obtained.…”